1. Field of the Invention
The present invention relates to a vehicle gaseous fuel supply system that includes a high pressure filter that removes impurities from high pressure gaseous fuel supplied from a tank, a primary pressure-reducing valve that reduces the pressure of the gaseous fuel from which impurities have been removed by the high pressure filter, a solenoid cut-off valve disposed between the high pressure filter and the primary pressure-reducing valve, safety means that operates in response to the output pressure of the primary pressure-reducing valve exceeding a set pressure, and a secondary pressure-reducing valve that further reduces the pressure of the gaseous fuel whose pressure has been reduced by the primary pressure-reducing valve and supplies it to an injector of an engine.
2. Description of the Related Art
Conventionally, such a system is already known in, for example, Japanese Patent Application Laid-open No. 11-270718, wherein a filter, a solenoid cut-off valve, a primary pressure-reducing valve, a relief valve, and a secondary pressure-reducing valve are integrated on a common regulator body, thereby forming a regulator.
In the above-mentioned conventional arrangement, since a high pressure section up to the primary pressure-reducing valve and a low pressure section after the primary pressure-reducing valve are integrated on the common regulator body, the regulator body must be made of a material that is compatible with the high pressure section. The material of the regulator body therefore has a greater strength than is required for parts related to the low pressure section, and there is further room for cost reduction. Furthermore, since a large number of components are integrated on the regulator body, the arrangement of passages in the regulator body becomes complicated, and the machining applied to the regulator body becomes correspondingly more difficult. Moreover, the dimensions of the regulator body increase, thus causing restrictions on the layout relative to other components when the regulator is mounted on a vehicle.
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to provide a vehicle gaseous fuel supply system that reduces the dimensions of a regulator in which a plurality of components are integrated, thereby lessening restrictions on the layout, and simplifies the arrangement of passages in a regulator body, thereby making the machining easy and achieving a reduction in cost.
In order to accomplish the above-mentioned object, in accordance with a first aspect of the present invention, there is proposed a vehicle gaseous fuel supply system that includes a high pressure filter that removes impurities from a high pressure gaseous fuel supplied from a tank, a primary pressure-reducing valve that reduces the pressure of the gaseous fuel from which impurities have been removed by the high pressure filter, a solenoid cut-off valve disposed between the high pressure filter and the primary pressure-reducing valve, safety means that operates in response to the output pressure of the primary pressure-reducing valve becoming equal to or exceeding a set pressure, and a secondary pressure-reducing valve that further reduces the pressure of the gaseous fuel whose pressure has been reduced by the primary pressure-reducing valve and supplies it to an injector of an engine, wherein the high pressure filter, the solenoid cut-off valve, and the primary pressure-reducing valve are disposed on a common regulator body to form a regulator, the regulator body having a passage providing a connection between the high pressure filter and the solenoid cut-off valve, a passage providing a connection between the solenoid cut-off valve and the primary pressure-reducing valve, and an exit passage having one end connected to the primary pressure-reducing valve, and wherein, between the safety means and the secondary pressure-reducing valve which are connected to the other end of the exit passage, at least the secondary pressure-reducing valve has a valve housing formed as a body separate from the regulator body.
In accordance with the above-mentioned arrangement of the first aspect, among the high pressure filter, the solenoid cut-off valve, the primary pressure-reducing valve, the safety means, and the secondary pressure-reducing valve, the high pressure filter, the solenoid cut-off valve, and the primary pressure-reducing valve which are on the high pressure side are integrated on the regulator body to form the regulator, the arrangement of the passages in the regulator body is simplified in comparison with the conventional regulator formed by integrating the whole of the high pressure section and the low pressure section, and the machining of the regulator body becomes correspondingly easier. Moreover, the regulator can be made compact, and when it is mounted on a vehicle, restrictions on the layout relative to other components can be lessened. Furthermore, since the valve housing of at least the secondary pressure-reducing valve between the safety means and the secondary pressure-reducing valve which are on the low pressure side, is formed as a body separate from the regulator body, the valve housing of the secondary pressure-reducing valve can be formed from a material having a comparatively low strength, thereby achieving a reduction in cost.
Furthermore, in accordance with a second aspect of the present invention, in addition to the first aspect, there is proposed a vehicle gaseous fuel supply system wherein a mounting face for providing said other end of the exit passage with an opening provided on the outer face of the regulator body, and bodies each having a low pressure passage and equipped with safety means of different types operating in response to the pressure of the low pressure passage are selectively mounted in a detachable manner on the mounting face so that the low pressure passage communicates with said other end of the exit passage. In accordance with the above-mentioned arrangement, one of the plural types of safety means can be selectively connected to the regulator, thereby enhancing the multi-purpose feature when the gaseous fuel supply system is mounted on a vehicle.
Furthermore, in accordance with a third aspect of the present invention, in addition to the above-mentioned arrangement of the second aspect, there is proposed a vehicle gaseous fuel supply system wherein the plural types of safety means are a pressure switch that determines the cut-off timing of the solenoid cut-off valve and a relief valve. In accordance with the above-mentioned arrangement, it is possible to freely select preventing a high pressure equal to or exceeding the set pressure from being applied to the secondary pressure-reducing valve by activating the solenoid cut-off valve so that it closes when the output pressure of the primary pressure-reducing valve becomes equal to or exceeds the set pressure; or preventing a high pressure equal to or exceeding the set pressure from being applied to the secondary pressure-reducing valve by releasing a part of the gaseous fuel output from the primary pressure-reducing valve when the output pressure of the primary pressure-reducing valve becomes equal to or exceeds the set pressure.
The above-mentioned object, other objects, characteristics and advantages of the present invention will become apparent from explanations of preferred embodiments that will be described in detail below by reference to the appended drawings.